Field of the Invention
The present invention relates to a fuel supply apparatus which is used for supplying fuel to a supply destination. More specifically, the present invention relates to a fuel tank that stores fuel, and a fuel pipe or the like that is interposed between the fuel tank and the supply destination (an engine or the like).
The present invention also relates to an aircraft including the fuel supply apparatus.
Description of the Related Art
Fuel supplied to an engine of aircraft is stored in an inner portion of a main wing used as a fuel tank. The fuel in the fuel tank is extracted from the fuel tank by a fuel pump, and is fed to the engine through a fuel pipe.
In engines of not only aircraft but of all kinds, generally, combustion efficiency is lowered when fuel contains water. Thus, there has been known a technique for separating and removing water from fuel by settling water by use of a filtering device having a porous membrane through which only water out of fuel and water passes (Japanese Patent Laid-Open No. 05-231257), or by adding a carbon-based material (a pellet of carbon black or the like) to fuel, stirring the carbon-based material and the fuel, and coagulating and solidifying the carbon-based material and the fuel to separate them from water (Japanese Patent Laid-Open No. 11-347304).
In aircraft, the temperature of surrounding outside air becomes extremely low along with an increase in flight altitude.
When fuel tanks of not only aircraft but of all kinds are cooled in a subfreezing environment, and fuel in the tanks is also cooled, water in the fuel freezes. In this case, an ice grain does not pass through the filtering membrane, and the fuel and the carbon-based material are not coagulated and solidified well. Thus, it becomes difficult to separate the water from the fuel.
Therefore, the water contained in the fuel may not be sufficiently removed, and the water in the fuel may solidify in a fuel pipe and adhere to an inner wall of the pipe. If the inside of the fuel pipe is narrowed by the adhesion of ice, the fuel becomes difficult to flow in the fuel pipe, so that fuel supply to the engine is disturbed.
Moreover, the ice adhering to the inside of the fuel pipe could fall away from the fuel pipe at once, and a lump of ice could block the inside of the fuel pipe or a fuel inlet of the engine due to an increase in outside air temperature along with a decrease in the altitude of aircraft, an increase in the flow rate of fuel by an increase in thrust, or due to vibration.
Furthermore, when the filtering membrane is used, the filtering membrane may be clogged. Thus, frequent maintenance and replacement of the filtering membrane are required. Also, when the carbon-based material is added, a tank to which the fuel is transferred from the fuel tank is required for separating the fuel and moisture by coagulation and solidification by adding the carbon-based material.
It is very difficult to provide the filtering device and the tank separately from the fuel tank in aircraft in which a decrease in weight is strongly demanded.
The present invention has been accomplished in view of such circumstances, and an object of the present invention is to provide a fuel tank, a fuel pipe, and an aircraft capable of ensuring fuel supply even when water contained in fuel freezes.